Manufacturing method for thin resin molded products

Abstract

To provide a method of manufacturing a thin-profile resin molding that is less likely to have a hole.SOLUTION: A method of manufacturing a thin-profile resin molding having an approximately rectangular shape with a length in a long side direction of 65 mm or more and 120 mm or less and a length in a short side direction of 30 mm or more and 70 mm or less, and having a planar portion with a thickness of 0.20 mm or more and 0.65 mm or less and a side wall portion extending from a peripheral edge of the planar portion comprises the steps of: preparing a mold corresponding to the thin-profile resin molding; melting a resin material containing at least polypropylene, injecting the molten resin material into the mold using an injection machine with an injection speed of 140 to 400 mm / sec, and filling the resin material in a molding region defined in the mold; cooling the resin material filled in the molding region of the mold while keeping a predetermined pressure; and taking a solid matter of the cooled resin material out of the mold as the thin-profile resin molding.SELECTED DRAWING: Figure 6

Claims

1. A method for manufacturing a thin resin molded product having a substantially rectangular shape with a length of 65 mm or more and 120 mm or less in the long side direction and a length of 30 mm or more and 70 mm or less in the short side direction, and a thickness of 0.20 mm or more and 0.65 mm or less, and a side wall portion extending from the periphery of the flat portion, A step of preparing a mold corresponding to the thin resin molded product, A step of melting a resin material containing at least polypropylene, injecting the molten resin material into the mold using an injection machine at an injection speed of 140 to 400 mm / second, and filling the molded area defined within the mold with the resin material, A step of cooling the resin material filled in the molding region of the mold while maintaining it at a predetermined pressure, The process of removing the cooled solid resin material from the mold as the thin resin molded product, A method for manufacturing thin resin molded products.

2. In the filling step, the molten resin material is injected into the mold by the injection machine at an injection speed of 200 to 350 mm / second. A method for manufacturing a thin resin molded product as described in claim 1.

3. In the cooling step, the filled resin material is cooled while maintaining a pressure of 65 to 100 MPa. A method for manufacturing a thin resin molded product as described in claim 2.

4. In the cooling step, the filled resin material is cooled while maintaining a pressure of 65 to 80 MPa. A method for manufacturing a thin resin molded product as described in claim 3.

5. In the filling step, the molten resin material is injected into the mold by the injection machine at an injection speed of 140 to 270 mm / second. A method for manufacturing a thin resin molded product as described in claim 1.

6. In the cooling step, the filled resin material is cooled while maintaining a pressure of 15 to 45 MPa. A method for manufacturing a thin resin molded product as described in claim 5.

7. In the filling step, the resin material is melted and injected at a temperature of 170 to 230°C. A method for manufacturing a thin resin molded product as described in claim 1.

8. The melt flow rate of the polypropylene contained in the resin material is 17 to 33 g / 10 min. A method for manufacturing a thin resin molded product as described in claim 1.

9. The resin material comprises 60 to 80 parts by mass of the polypropylene and 20 to 40 parts by mass of biomass-derived polyethylene. A method for manufacturing a thin resin molded product as described in claim 1.

10. The melt flow rate of the biomass-derived polyethylene is 5 to 25 g / 10 min. A method for manufacturing a thin resin molded product as described in claim 9.

11. In the filling step, the molten resin material is injected into the mold by the injection machine at an injection speed of 140 to 270 mm / second. In the cooling step, the filled resin material is cooled while maintaining a pressure of 15 to 70 MPa. A method for manufacturing a thin resin molded product as described in claim 9.

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